This invention relates to gas-cooled dynamoelectric machines, and more particularly to a generator with modifications to the region where the ascending diagonal cooling gas flow passages emerge into the gap between the rotor and the stator.
Large turbine-generators and other similar dynamoelectric machines are limited in capacity by the ability of the cooling system to remove heat from the rotor. As shown in U.S. Pat. No. 3,348,081 to D. M. willyoung, the cooling system can be provided by radial ducts in the stator, a gap pickup rotor to scoop hydrogen gas coolant from the gap for cirulation through internal passages in the rotor, and fans and heat exchangers to produce a coolant flow to ventilate the machine. There are large clearances of approximately three to four inches between the stator and rotor, hence an attempt to use fan or blower pressurization to drive the cooling hydrogen flow through the rotor tends to be thwarted by excessive leakage in this clearance. Partial radial baffles may also be used to restrict axial leakage from an outlet rotor zone to an inlet rotor zone.
In my commonly assigned, co-pending application, Ser. No. 470,061 (now U.S. Pat. No. 3,906,265), filed May 14, 1974, I have shown a similar machine wherein one or more honeycomb stator inserts comprising a large cell honeycomb baffle structure defining radial passages for coolant flow are mounted on the stator extending into the gap between the stator and rotor of a gas-cooled dynamoelectric machine such as a generator of the foregoing type. Preferably, a plurality of honeycomb insert sectors are mounted adjacent to one another in the gap so as to be substantially peripherally continuous. The honeycomb baffling functions dually as axial baffles to restrict axial leakage of the coolant especially between cooling zones, and as peripheral baffles to effect a material reduction of the swirl flow in the gap. Since the relative velocity of the gas with respect to the rotor inlet and outlet ducts is increased, higher pumping pressures of coolant through the rotating rotor are realized for improved rotor cooling. Reduced axial leakage and nearly complete circumferential closure of the gap results in improved zone pressurization and utilization of the fans or blowers circulating the coolant. In that application, I have also disclosed in FIG. 6 a variation of the rotor, wherein the windings are provided with radial, rather than diagonal passages, connecting to axial ducts within the rotor for circulation of coolant from an inlet to an outlet duct. However, the use of diagonal passages is accepted in the art as an excellent design, and the present invention was developed to improve the cooling of machines provided therewith.